2018-06-11
Sparse stuff:
Each processor has a specific set of instructions, called Instruction Set Architecture (ISA)
Bit: transistor/switch (on or off)
Assembly language
def. a low-level symbolic code converted by an assembler
ex.
> mov a1, 061h :
load in register a1 the content of memory location of adress 061h
easier to write but codes are extremely long and hard to read and understand
high-level languages
easier to write and read algorithms
> 1972: Dennis Ritchie at Bell telephone
Labs develops the C language
> 1979: Bjarne Stroustrup at Bell Labs
design and implement C++
(C with classes)
More sparse stuff:
compiler: g++
command line debugger: gdb
- not really practical to use
Integrated Development Environment (IDE)
##:- single line:
// - multiple lines:
/* ... */
- single line:
multiple file programs and header files
sparse stuff:
types
porto workshop week
operations for variable modification
prefix and postfix
implicit type conversion
ex.
conditional statement
pointer (dereference operator *)
a pointer is a variable that stores the address of another object
always initialize a pointer, *, with the value zero
pointers can be assigned addresses of other variables via the address-of operator (ampersand) & - the types of the variable and the pointer have to match
exs.
size
- the size of pointer doesn’t depend on its type
arrays
what Stroustroup says about:
declaration
indexes range from 0 to
size-1to access an element use the subscript operator
[]or through a pointer
boundary checking: C/C++ compiler does no boundary check. Using out of range indexes is not detected by compiler and results in computation errors
array list initialization
sizeof an array
returns the number of bytes allocated for the entire array
multidimensional arrays
for readability, use nested curly brackets
pointer arithmetic (with an ex)
- number of elements should be constant and could not be changed later
dynamic memory allocation
ex.
program memory
a programs memory is divided into
code area: compiled program (executable)
globals area: global variables
heap: dynamically allocated memory
stack: parameters and local variables
2018-07-02
strings
c++ 11 doesn’t allow string literals to be assigned to non-const char *
string concatenation
std::string // string class (data type)
string str = "Hello";
index range is 0 to
str.length()-1
common string methods
<cctype>: character manipulation
user-defined types
struct: sequence of elements (called members) of arbitrary typesunion: astructthat holds the value of just one of its elements at any one timeenum: a type with a set of named constants (called enumerators)
arrayaggregate data of the same type,structaggregate data of arbitrary type
structure
elements of a
structare called members or fieldsmember selection operator is the
.selecting a
structfield from a dereferenced pointer to thestructuses different operator:->
enumeration
exs.
2018-07-04
passing arguments by reference
What if I want to return more than one result with just one function?
Allow the function to modify the values of an argument: pass parameters by reference
exs.
static variable
ex.
2018-07-16
I/O stream library,
<iostream>, in order to display output to the standard output device (generally the screen) and get input from standard input device (generally the keyboard)
<fstream>extends<iostream>with additional features that make it possible to read from and write to (text and binary) files
A
streamcan be thought of as a sequence of bytes of infinite length that is used as a buffer to hold data that is waiting to be processed
declare a stream variable
open a file…
partial list of I/O manipulators
formatted stream input
extraction operation stops at white spaces
ex.
test if extraction/insertion has succeeded using the fail() method
operations for input streams
operations for output streams
2018-07-18
custom data types
a type is a concrete representation of a concept; e.g. float is a representation of real numbers
we design a new type to provide a definition of a concept that has no direct counterpart among the built-in types
the
classconstruct allows to define C++ classes, a tool for creating new types that can be used as conveniently similarly to the built-in types
classes main features
a
classis a user-defined type
member functions can define the meaning of initialization (creation), copy, move, and cleanup (destruction)
the public members provide the
class’s interface and theprivatemembers provide implementation details: encapsulation
a
structis aclasswhere members are by default public
by default, if you don’t specify, everything in the
classis private
ex.
the function implementation can be included in the class definition or outside. generally, code is textually separated into two files with the same name as the class / struct and different extensions
an implementation file .cpp for most member function implementations
a header file for the class / struct definition
access control
“user code”: code that uses the data type. “user” here doesn’t designate the application user
to restrict manipulation of the data members, use a
classinstead of astruct
in a
class, by default, the members are private i.e. accessible only by member functions
by restricting access to data members, a need for an initialization function arises e.g. Date::init
the private access specifier can be also used to emphasize the privacy of data members; both access specifiers can be used many times within the same class definition
Sys.time()## [1] "2018-07-18 14:14:59 +03"